Yes. Under 745.226(a)(5), individuals performing lead-based paint activities must be certified, so all self-employed persons must be certified as individuals in the appropriate discipline(s).
In addition, the definition of certified firm at 745.223 includes sole proprietorships that perform lead-based paint activities. The definition of certified firm also includes other business entities that perform lead-based paint activities. This includes all other one-person businesses that would not be considered to be sole proprietorships.
Under 745.226(f)(1), all firms performing or offering to perform lead-based paint activities must be certified. Therefore, any person who is self-employed or operating a one-person business which performs or offers to perform lead-based paint activities, must be certified in the appropriate individual disciplines as required by 745.226(a) and must also be certified as a firm under 745.226(f).